Electron image tube fiber optical face plate seal structure



ELECTRON IMAGE TUBE FIBER OPTICAL FACE PLATE SEAL STRUCTURE E5 1%? R. J. MEY

Filed June 12, 1964 FIGJ.

INVENTGR: RQBERT d. NEY,

This invention relates to an improved seal structure and more particularly to an improved sealing structure including a stress accommodating intermediary metallic support between two non-metallic members.

Television camera tubes are ordinarily subjected to very.

stringent operating conditions with respect to thermal stresses and vibrational shocks which deletcriously affect their optimum operative life cycle. Therefore, great care must be taken to provide effective structural interrelationship of the integral parts including the sealing or bonding means employed for'the attachment of various members in such tubes. Particularly, a high degree of care is involved, and considerable cn'ticality attached to, the sealing or joining means which are employed to join the camera tube optical face plateto the tube body. The face plate is ordinarily an optical member such as various known opti-. cal glasses, sapphire, etc. However, there is a marked difference in the thermal coethcients of expansion between the mentioned materials and the hard glass of the tube body leading to serious sealing problems at their juncture. It has also been proposed to employ a fiber optics face plate for television camera tubes because a fiber optics face plate is superior to the former optical glass face plate for some applications. However, together with the considerable'difierence in thermal expansion of a fiber optic element and the glass body of the camera tube, the internal bond of a fiber optic plate is not of high strength, a feature which also introduces a serious problem of sealing the face plate to the tube body.

Accordingly, it is an object of this invention to provide an improved seal.

It is a further object of this invention to provide an improved glass or ceramic-to-mctal seal.

It is a still further object of this invention to provide a combined sealing method and apparatus for the joining of a television camera tube faceplate to thetube body.

it is yet another object of this invention to provide an improved supporting means and sealing assembly for a fiber optics face plate for camera tubes for the joining thereof to a glass tube body.

it is another object of this invention to provide an improved sealing and intermediate metallic supporting means for the joining of a face plate to a camera tube body. v

. it is yet another object of this invention to provide a bi-mctallic intermediate sealing and supporting means between the optical face plate and glass body of an image orthicon camera tube.

Briefly described, this invention in one form includes an annular frame or flange supporting member on which there is concentrically positioned an improved optical face plate. This frame member is convoluted, dished or is otherwise concave or convex from the periphery toward a central opening defined by a very thin central shelf. The shelf supports the optical face plate in sealed relationship. At the same time, this frame member is concentrically positioned within and joined at its periphery to a thin metal cylinder. The other edge of the cylinder is joined concentrically with the rim of a mating, abutting,

hard-glass tube body.

This invention will be better understood when taken in connection with the following description and drawingsin which FIG. 1 is a cross-sectional illustration of a portion of an image orthicon tube illustrating the face plate attach- I mounting flange of this invention.

. Without references to the numerous kinds of face plate materials, and the particular kinds of sealing materials (brazes, solders, etc.) employed, it is a common problem that in all instances the sealing means or attaching arrangement must provide for high thermal stresses and shock stability and maintain effective face plate alignment and spacings under adverse operating conditions. One of the most contributing factors to face plate seal failures and other types of failures is the thermal mismatch condition between the face plate material and the tube body.

. of such materials as different glasses, fiber glass, sapphire,

and other such ceramics, to the hard-glass body 11, the heretofore mentioned problems of misalignment, stability,

' and good seals quickly arise. It has been discovered that efiective sealing and attaching means which overcome the mentioned problems may be provided through the use.

of a particularly formed bi-rnetallic member.

Gne specific feature of a bi-metallic member relates to the use of predetermined metallic elements as the intermediary member for sealing one ceramic material, i.e., the face plate, to the tube glass body. For example, the bimetallic member includes one particular metal which is joined or otherwise sealed to the face plate, and which is so chosen as to provide not only a proper seal to the face plate but also be closely approximate the coefficient of expansion of the face plate itself. The other metal of th bi-metal element is chosen for joining to the hard-glass tube body and this metal is also so chosen as to provide not only the proper seal but also a close approximation of the thermal expansion characteristics of the tube glass body.'Finally, a particular joining means, such as welding, is then adapted to join the chosen metal elements at an intermediate position where the difference of expansion characteristics may be better tolerated than at either the face material or the glass body. One example of this invention is illustrated in FIG. 1 by the sealing arrangement M. The sealing arrangement 14 includes a thin metal annulus, or cylinder is, which is concentrically positioned on the end of the glass section 13 and abuts thereto. More particularly, one edge of cylinder 15, which is illustrated as 16, is embedded within the glass wall material of section 13. The particular sealing means which is employed to join the edge 16 to the glass wall 13 may take the form of those well known prior art glass-tometal seals where end 16 is embedded in the glass tube 13 by heat softening the glass.

I The face plate portion of the arrangement 14 includes a suitable thin metal flange or frame member 17 providing a concentric opening 33, over which the face plate 19 is attached. It has been discovered that optimum results are only obtained in the practice of this invention when the flange member 1 is suitably convoluted so that a major portion of the frame member 17 and face plate 19 does not lie in common plane transverse to and (d) said metal member and said ceramic member having predetermined and close coefficients of expansion,

(c) a metal support ring surrounding said metal numto said support ring in edge abutting relationship,

-(h) said metal support ring having a coetlicient of 4. An image orthicon camera tube having a tube section and a target section, said target section comprising in combination (a) an annular metal alloy member of from about oer and peripherally joined thereto, 0.015 to about 0.020 inch thickness, having a con- (f) said metal support ring having a significantly difiercentric convolution therein,

cut coetficient of expansion than said annular metal (b) said metal alloy including at least one metal taken member and said ceramic disk member, from the group consisting of iron, nickel, chromium,

( g) said metal support ring having a coefficient of extitanium,

pausion closely approximating that of a further (c) said metal alloy member having an axially desupport to which it is adapted to be sealed. pressed reduced thickness radially inwardly extend- 2. An electron image tube having a face platc section ing annular supporting surface defining a central comprising 7 M aperture,

(a) a thin annular metal member, (d) said annular supporting surface having a reduced (b) said member having a large annular convolution thickness in the range of about 0.003 to about 0.006

therein, inch,

(c) said metal member having a reduced thickness (6) a fiber optic face plate member of a larger diannular supporting surface adjacent said convolution ameter than said aperture and concentrically sealed and defining a central aperture, to said supporting surface for flexible support there- (d) said annular supporting surface having a reduced by with the outside diameter of said supporting surthickness in the range from about 0.003 to about face being slightly radially larger than said face plate 0.006 inch, to have a seal material cover the exposed juncture,

(e) a fiber optic face plate member overlapping. said said face plate having a constant thickness over the aperture and concentrically sealed to said annular diameter thereof, supporting surface for flexible support thereby with (f) said metal alloy member and said ceramic member said supporting surface parallel to the face plane having predetermined and close coefiicients of er:- of said face plate, pension,

(f) said annular metal member and said ceramic mern- (g) an annular difierent metal alloy supporting ring her having predetermined and close eoenicients of surrounding said metal alloy member and periphcxpansion, orally joined thereto,,

(g) a cylindrical metal support ring coanially s'ur- (b) said metal alloy supporting ring having a signifirounding said annular metal member and periphcantly different coefficient of expansion than said erally joined thereto at one edge, annular metal alloy member and said fiber optic face (b) said metal support ring having a significantly Plato,'

different coefiicient of expansion than said annular 3 d a gla s cylinder concentrically sealed to said metal member and said fiber optic face plate, Supporting ring,

(i) said metal support ring having a coefiicient of can (i) Said metal Support ring having 3 Coefficient of pansion closely approximating that of a further sup expansion closgly approximating that Of Sald glass port to which it is adapted to be sealed. ylin er t which it is sealed.

3. An electron image tub apparatus h vi a t b 40 5. A method of assembling a face plate arrangement section and a target section, said target section compris a lube y which Comprises lag in combination (a) providing an annular metal member adapted to (a) an annular metal alloy member of from about ngly Support an optical face plate,

0.015 to 0.020 inch thickness having an annular large Welding Said annular metal member concfintficany onvolution therein With 3 cylindrical metal member,

- (b) said metal member having a reduced thickness forming 81355 bead 0B the exposed edge 0f Said radially inwardly extending annular supporting sur- Cylindrical member, face adjacent said convolution and defining a cenconcentrically attaching a glass cylinder o id tral aperture, bead, and

(c) said annular supporting surface having a r du ed so (e) sealing said face plate to saidannular member,

thickness in the range from about 0.003 to about Sealing Said glass cylinder concentrically lo a 0.006 inch, camera tube body.

(d) a fiber optic face plate member of a diameter larger than said aperture and concentrically sealed RQEQWQQBS Cited igeriilytlil supporting surface for flexible support UNITED STATES PATENTS (e) a different metal alloy support ring surrounding 1'964952 2/1934 Klmckmann 189 36-5 said annular metal member and peripherally joined 2584653 4/1952 Alpert 189*36'5 thgmto, i 2,647,070 7/1953 7 Litton 287-189 (f) said metal support ring havinga'significanfly diner. 2,708,250 5/1955 D y 313- 2s2 ent coelficient or" expansion than said annular tal. 2,873,397 2/ 1959 G y 313--89 member, 3,213,308 10/1965 Feibelman 313...,39'

(g) and a glass cylinder adapted for coaxially sealing 4 2 4/ 6 Bohun 313-89 55 EAMES W. LAWRENCE, Primary Examiner, expansion closely aproximating that of said glass R.- JUDD, Assistant Examiner.

I y er. 

1. IN A FACE PLATE ARRANGEMENT FOR AN ELECTRON IMAGE TUBE, THE COMBINATION COMPRISING (A) A THIN ANNULAR METAL MEMBER HAVING A LARGE CONCENTRIC ANNULAR DEPRESSION AXIALLY THEREIN SURROUNDING AN APERTURE, (B) SAID METAL MEMBER HAVING A REDUCED THICKNESS RADIALLY INWARDLY DIRECTED ANNULAR SUPPORTING SURFACE ADJACENT SAID DEPRESSION AND DEFINING SAID APERTURE, (C) A FIBER OPTICAL FACE PLATE MEMBER OVERLAPPING SAID APERTURE AND CONCENTRICALLY SEALED TO SAID SUPPORTING SURFACE FOR FLEXIBLE SUPPORT THEREBY WITH SAID SUPPORT SURFACE PARALLEL TO SAID PLATE, (D) SAID METAL MEMBER AND SAID CERAMIC MEMBER HAVING PREDETERMINED AND CLOSED COEFFIFIENTS OF EXPANSION, 